Finned cylinder



Dec. 26, 1939. o. s. HERSEY FINNED CYLINDER Filed Dec. 31, 1938 INVENTOR. 170naf2 5 lafi rsz-gy BY Jim/uh M A TTORNEY Patented Dec. 26, 1939 FINNED CYLINDER Donald S. Hersey, West Hartford, Conn., assignor to United Aircraft Corporation, East Hartford, Oonm, a corporation of Delaware Application December 31, 1938. Serial No. 248,677

3 Claims.

radiating structures and has particular reference to an improved heat radiating structure for a device such as a cylinder of an lntemal combustion engine.

An object of the invention resides in the pro vision of an improved heat radiating structure of the character indicated in which the provision of the heat radiating structure is simplified by utilizing preformed heat radiating elements and securing the elements in proper arrangement to the surface of the structure from which the heat is to be radiated.

A further object resides in the provision of a finned heat radiating structure embodying preformed sheet metal fins provided with integral flanges or extensions to constitute boundaries-for cooling air passages.

A still further object resides in the provision of a finned heat radiating structure embodying preformed sheet metal fins having integral extensions adapted to contact adjacent fins to reinforce the structure.

Other objects will be more particularly pointed out hereinafter or will become apparent as the description proceeds.

In the accompanying drawing in which like reference numerals are used to designate similar parts throughout there is illustrated a suitable example of a heat radiating structure arranged according to the invention. The drawing, however, is for the purpose of illustration only and is not to be taken as in any way-limiting or restrlcting the scope of the invention as set forth in the accompanying claims.

In the drawing, Fig. 1 is a diagrammatic view of an internal combustion engine having cylinders provided with heat radiating fins, and cooling air guides or baflies for constraining the cooling air to flow through the finned structure, and

an enclosing cowl for the engine.

Fig. 2 is a transverse sectional view through a finned portion of one of the engine cylinders.

Fig. 3 is a longitudinal sectional view of a tresmentary portionof the engine cylinder shown in Fig. 2 taken on the line 3-3 of Fig. 2.

Fig. 4 is a longitudinal sectional view of a fragmentary portion of the cylinder shown in Fig. 2 taken on the line 4-4 of Fig. 2.

Fig. 5 is a schematic illustration of the improved fin and baflie construction applied to a single row engine, and

Fig. 6 is a schematic illustration of the improved fin and baffle construction applied to a two row engine.

This invention relates to improvements in heat Referring to the drawing in detail and particularly to Fig. 1, the numeral Ill generally indicates the crankcase portion of an internal combustion engine such as a radial air-cooled engine of a type conventionally'employed for the pro 6 pulsion of aircraft. While the improved heat radiating structure is shown, for the sake of convenience, as applied to an air-cooled aircraft engine it is to be understood that the invention is in no way limited in its application to an air- 10 craft engine or to any kind of powerplant since it might obviously be applied to dissipate heat from various other devices such as air or gas compressors, space warming radiators, fluid heating or cooling devices and variousother de- 15 vices where such a heat radiating or transferring structure would be useful.

In the application illustrated the numeral l2 indicates the cylinders projecting radially from the crankcase portion lll'of the engine. These 20 cylinders are provided with finned barrel and head portions as indicated at M and I6, respectively, and are enclosed in the open ended'stream lined cowl l8. Baffles 2|] are provided to constrain the air flowing through the cowl l8 to flow 25 past the cylinders l2 in intimate contact with the cooling fins of the cylinders. As the fin and baflie structure for all of the cylinders may-be similar an illustration and description of the structure of only one cylinder is considered suifl- 30 cient for the purpose of this disclosure.

The barrel portion of each cylinder [2 may be a relatively thin walled tube, as particularly shown in Figs. 2 and 3, preferably'made of some strong and durable material such as steel. The 35 head portion may be a casting or forging of any suitable structure and material and may be' provided with heat radiating'fin's either preformed and secured thereto, as shown in Figs. 2, 3 and 4 in connection with the barrel portion M, or may 40 be provided with integral heat radiating fins in a manner well known to the art. For the sake of convenience the improved fin structure is illustrated as applied to the barrel portions of the cylinders. prises an annular member formed up of sheet metal and preferablyprovided around its inner circumference with a continuous upstanding flange as indicated at 22. The flanges 22 are preferably of such dimensions that the edge of 5 each flange touches the adjacent portion of the next fin when the fins are assembled in properly spaced relation upon a cylinder, as is particularly shown in Fig. 3. If this is the case theflanges 22 serve to space the fins the correct dis- 55 Each such barrel portion fin l4 comtance apart as well as to reinforce the inner edges of the fins and provide sumcient area for attachment of the flns to the surface of the barrel of the cylinder II. The inner surfaces of the flanges 22 are preferably bonded to the surface of the cylinder by some means which not only rigidly secures the fins to the cylinder but at the same time provides a substantially uninterrupted heat conduction from the cylinder walls to the surrounding fins. Examples of suitable means are welding or brazing or casting the edges of the fins into a layer of metal, such as aluminum cast onto the outside of the cylinder or cylinder head. At their outer circumferences the fins may be provided with sectional flanged portions 24, similar to the flanges 22 except that they extend only a portion of the way around the outer circumference of the fins, as is particularly shown in Fig. 2. The edges of the flange portions 24 also contact the juxtaposed surfaces of adjacent fins and constitute an outer wall for the finned structure for the area over which these flanged portions extend so that air flowing through the flnned structure is confined between the flanges 22 and the corresponding outer flange portions 24 and the stream is divided by the annular portions of the fins.

Near the ends of the flanged portions 24 the bailie entrance members are attached in such a manner that the baflle members on adjacent cylinders engage or overlap to obstruct the flow of air between the cylinders and constrain all of the air flowing through the cowl I8 or, in any case, the part of the cooling air flowingpast the cylinder barrels, to flow through the flnned structure of the cylinders. If desired, exit guide members 26 may be provided at the ends of the flange portions 24 opposite the ends to which the bailles 20 are attached to direct or control the air stream leaving the finned structures or, in the case of a two-row engine these members 28 on the front row of cylinders may be utilized to cooperate with baflie members 20 on the rear row of cylinders to close the inter-cylinder spaces.

The fin elements may also be provided intermediate the flanges 22 and 24 with integral beads or ridges 28 of substantially the same height as the flanges. These ridges may be arranged in any manner as may be necessary or desired to control the flow of the cooling air through the finned structure and serve to divide the cooling air flow into separate streams and direct these streams around the cylinder in a manner calculated to most efficiently remove the excess heat from the cylinder and heat radiating fins. In the arrangement shown in Fig. 2 the beads or ribs 28 are designed to guide the air flow around the rear portion of the cylinder and prevent undue stratiflcation and pulling away of the air as it leaves the cylinder at the rear side thereof.

The fin circumference at the front of the cylinder between the baflle strips 20, and the portion between the guide vane 26 is left unflanged at the outer circumference, as is particularly indicated in Fig. 4, to permit free entry and exit or air to and from the heat radiating structure. Where the unflanged outer circumferential distance is relatively great, intermediate lugs may be provided, as indicated at 30 in Fig. 2, to maintain the proper interval between the various flns.

Although a barrel fin construction has been particularly illustrated for the purpose of disclosing the invention, the cylinder head fins may be constructed in a similar manner with only obvious modifications and, as pointed out above,

the finned construction may be applied to various devices in addition to internal combustion englnes.

In the single row arrangement particularly illustrated in Fig. 5 the attached side members or guide vanes 20' are brought together between the cylinders to some form of substantially air tight connection such as the butt joint indicated at 2|. These members then constitute inter-cylinder baflles which obstruct substantially all air flow between the finned surfaces of the cylinders and cause all of the cooling air to flow through the spaces between adjacent cylinder fins. In this arrangement the exit apertures at the rearward sides of the cylinders may be provided with suit-- able guide vanes or air vent conduits as indicated at 26 and the integral ribs 28 are provided in the individual fins to guide the cooling air about the cylinders to produce uniform cylinder temperatures and avoid temperature variations within localized areas.

In the two row arrangement, particularly illustrated in Fig. 6 the members 20 are utilized as air guide members to assist in distributing the air flow between the front row and the rear'row of engine cylinders. the space between the juxtaposed edges of two adjacent members 20 the amount of air supplied to each cylinder of the rear row may be accurately controlled and the quantity of air supplied to each row may be regulated. In this case the fins are provided with peripheral flanges and integral ribs, as explainedabove, and may be provided with air exit guide members 26, as described above. Only the cylinders of the front row are provided with the guide members 20, the cylinders of the rear row being each provided with a pair of baflle members as indicated at 32 which extend from the outer flanged portion of the rear cylinder flns to the adjacent outer flanged portion of the front cylinder fin to constitute air obstructing bailles across the spaces between each rear cylinder and the two adjacent front cylinders thereby obstructing the flow of air through the intercylinder spaces and constraining all of the cooling air to flow through the spaces between the individual cylinder fins.

While a particular embodiment has been hereinabove described and illustrated in the accompanying drawing for the purpose of disclosing the invention, it is to be understood that the invention is not limited to the construction and arrangement so illustrated and described but that such changes in the size, shape and arrangement of the various component elements may be resorted to as come within the scope of the subjoined claims.

Having now described the invention so that others skilled in the art may clearly understand the same, what it is desired to secure by Letters Patent is as follows:

1. A heat radiating structure comprising, a series of superposed spaced apart flns apertured to receive a heat radiating body, each of said fins having a flange surrounding the aperture for attachment to said body and one or more flanges spaced from said aperture surrounding flange adapted to cooperate with an adjacent fin to provide airflow channels between said fins, said flns also having integral curved ridges intermediate said flanges constituted by ribs formed up in said fins between the inner and outer edge of each fln to guide cooling air around said heat radiating body in close proximity thereto.

- 2. Cooling structure for the cylinders of an Obviously by controlling' internal combustion engine comprising, a group of preformed sheet metal fins surrounding a portion of the exterior surface of each cylinder and rigidly secured thereto, said fins being spaced apart to permit a flow of cylinder cooling air therebetween, integral flange portions at the outer edges of said fins extending across the respective interfin spaces to constrain the air flowing past said cylinders to fiow between said fins, and integral curved ridges on said fins intermediate the width of the respective fins to guide the air flowing between said fins around said cylinders to provide a substantially uniform distribution of cooling air entirely around the cylinders.

3. A cooling structure for a cylinder of an internal combustion engine comprising, a plurality of preformed annular fins apertured to receive said cylinder, a continuous flange on the inner circumference of each fln for attachment to the outer surface of said cylinder, discontinuous flanges on the outer circumference of each fln for defining air flow passages between the inner and outer circumferences of said fins, and curved intermediate integral beads in said fins between said inner and outer circumferences for guiding the air flowing between said fins in curved paths following the contour of said cylinder.

DONALD S. HERSEY. 

